Monoalkylated aromatic compounds are important for a variety of uses, especially as intermediate compounds in the manufacture of detergents. Two common reactions for producing monoalkylated aromatic compounds are alkylation of aromatic compounds, and transalkylation of polyalkylated aromatic compounds. Monoalkylated aromatic compounds include linear alkylbenzenes (LAB), which are used to form linear alkylbenzene sulfonates (LABS), a common compound used in detergents. Monoalkylated aromatic compounds also include such compounds as ethylbenzene and cumene which are important precursors for the production of styrene and phenols.
Monoalkylated benzenes are formed by reacting benzene with an olefin compound over a catalyst. One such catalyst is beta type zeolites and has been used for benzene alkylation commercially since 1996. Since then new catalysts have been developed and along with a better understanding, new processes. One aspect of benzene alkylation has been the use of high benzene to olefin ratios for the production of alkylbenzene production.
Currently, monoalkylated benzenes are desired, and polyalkylated benzenes are by-products that need to be removed or need to be recycled to try and produce more monoalkylated benzenes. The method of reducing the amount of polyalkylated benzenes is to increase the benzene to olefin ratio. However, the industry is striving to reduce the benzene to olefin ratio in order to save recycle fractionation and energy cost, and the usual method is to use many small beds with decreasing ratios as the benzene and olefins pass through successive beds, yet the lowest ratios tend to be about 5 at the final beds in the process.
Improvements in the process can save raw materials, energy, and reduce costs.